Field of the Invention
The invention relates to a surgical system and method and, more particularly, to a surgical system and method for verifying calibration of a surgical device.
Description of Related Art
Minimally invasive surgery (MIS) is the performance of surgery through incisions that are considerably smaller than incisions used in traditional surgical approaches. For example, in an orthopedic application such as total knee replacement surgery, an MIS incision length may be in a range of about 4 to 6 inches whereas an incision length in traditional total knee surgery is typically in a range of about 6 to 12 inches. As a result of the smaller incision length, MIS procedures are generally less invasive than traditional surgical approaches, which minimizes trauma to soft tissue, reduces post-operative pain, promotes earlier mobilization, shortens hospital stays, and speeds rehabilitation.
One drawback of MIS is that the small incision size reduces a surgeon's ability to view and access the anatomy. For example, in minimally invasive orthopedic joint replacement, limited visibility and limited access to the joint increase the complexity of assessing proper implant position and of reshaping bone. As a result, accurate placement of implants may be more difficult. Conventional techniques for counteracting these problems include, for example, surgical navigation, positioning the leg for optimal joint exposure, and employing specially designed, downsized instrumentation and complex surgical techniques. Such techniques, however, typically require a large amount of specialized instrumentation, a lengthy training process, and a high degree of skill. Moreover, operative results for a single surgeon and among various surgeons are not sufficiently predictable, repeatable, and/or accurate. As a result, implant performance and longevity varies among patients.
In orthopedic applications, one drawback of both MIS and traditional surgical approaches is that healthy as well as diseased bone is removed when the bone is prepared to receive the implant. For example, a total knee replacement can require removal of up to ½ inch of bone on each of three compartments of the knee.
Another drawback of both MIS and traditional orthopedic surgical approaches is that such approaches do not enhance the surgeon's inherent surgical skill in a cooperative manner. For example, some conventional techniques for joint replacement include autonomous robotic systems to aid the surgeon. Such systems, however, typically serve primarily to enhance bone machining by performing autonomous cutting with a high speed burr or by moving a drill guide into place and holding the position of the drill guide while the surgeon inserts cutting tools through the guide. Although such systems enable precise bone resections for improved implant fit and placement, they act autonomously (rather than cooperatively with the surgeon) and thus require the surgeon to cede a degree of control to the robot. Additional drawbacks of autonomous systems include the large size of the robot, poor ergonomics, the need to rigidly clamp the bone during registration and cutting, increased incision length for adequate robot access, and limited acceptance by surgeons and regulatory agencies due to the autonomous nature of the system.
Other conventional robotic systems include robots that cooperatively interact with the surgeon. One drawback of conventional interactive robotic systems is that such systems lack the ability to adapt surgical planning and navigation in real-time to a dynamic intraoperative environment. For example, U.S. patent application Ser. No. 10/470,314 (Pub. No. US 2004/0128026), which is hereby incorporated by reference herein in its entirety, discloses an interactive robotic system programmed with a three-dimensional virtual region of constraint that is registered to a patient. The robotic system includes a three degree of freedom (3-DOF) arm having a handle that incorporates force sensors. The surgeon utilizes the handle to manipulate the arm to move the cutting tool. Moving the arm via the handle is required so that the force sensors can measure the force being applied to the handle by the surgeon. The measured force is then used in controlling motors to assist or resist movement of the cutting tool. For example, during a knee replacement operation, the femur and tibia of the patient are fixed in position relative to the robotic system. As the surgeon applies force to the handle to move the cutting tool, the interactive robotic system may apply an increasing degree of resistance to resist movement of the cutting tool as the cutting tool approaches a boundary of the virtual region of constraint. In this manner, the robotic system guides the surgeon in preparing the bone by maintaining the cutting tool within the virtual region of constraint. As with the above-described autonomous systems, however, the interactive robotic system functions primarily to enhance bone machining. The interactive robotic system also requires the relevant anatomy to be rigidly restrained and the robotic system to be fixed in a gross position and thus lacks real-time adaptability to the intraoperative scene. Moreover, the 3-DOF configuration of the arm and the requirement that the surgeon manipulate the arm using the force handle results in limited flexibility and dexterity, making the robotic system unsuitable for certain MIS applications.
In view of the foregoing, a need exists for a surgical system that can replace direct visualization in minimally invasive surgery, spare healthy bone in orthopedic joint replacement applications, enable intraoperative adaptability and surgical planning, and produce operative results that are sufficiently predictable, repeatable, and/or accurate regardless of surgical skill level. A surgical system need not necessarily meet all or any of these needs to be an advance, though a system meeting these needs would me more desirable.
Furthermore, there is a need for a surgical system and method that can accurately verify the calibration of a surgical device. By verifying the calibration of a surgical device, the surgical system can accurately provide positional information to a user of the surgical device, thus enabling the user to locate the surgical device relative to the anatomy of a patient, despite the size of an incision used for MIS, and to minimize the amount of bone removed during a surgical procedure.